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From: izumi@pinoko.berkeley.edu (Izumi Ohzawa)
Newsgroups: comp.sys.next
Subject: Yet another way to dim your screen...
Keywords: screen saver, auto-dim
Message-ID: <1991May31.003447.9457@agate.berkeley.edu>
Date: 31 May 91 00:34:47 GMT
Sender: root@agate.berkeley.edu (Charlie Root)
Reply-To: izumi@pinoko.berkeley.edu
Organization: University of California, Berkeley
Lines: 60

On my cube, the default auto-dimming doesn't lower the brightness
of the screen enough.  Although there are numerous screen dimmers,
most of them require you to run a process while dimming is in effect.
I don't want to run a process just to do screen dimming, especially
when there is an auto-dimmer built into loginwindow.
I looked for ways to lower the auto-dim brightness, and sure enough
found this in <nextdev/evsio.h>.
----
/* Device control ioctls.  Note that these set the current value
   but do not affect parameter RAM.  */

#define EVSIOSADB _IOW('e', 104, int)   /* Set AutoDim Brightness */
#define EVSIOCADB _IOR('e', 105, int)   /* Current AutoDim Brightness */
----

Running the program below once when you are logged in shows that the
default auto-dim brightness is 15, and this program will set it to 0,
making the screen A LOT dimmer than the standard setting.  The white
regions are faintly visible on some monitors, but it is dark enough for me.
Other monitors are completely blanked by this.
This is more-or-less what I wanted.

THE PROBLEM is that the auto-dim brightness is reset to 15 on
next workspace login.  It seems to persist after logout, though.

So, my questions today are:
[1] Does anybody know how one can make the auto-dim brightness value
permanent?

[2] Where is the "parameter RAM" the comment in evsio.h is referring to?


--- cut -- setautodim.c ---------------
#include <nextdev/evsio.h>
#include <libc.h>

int main( int argc, char **argv)
{
  int o_dim,n_dim;
  int evs=open( "/dev/evs0",O_RDWR);

  if ( evs < 0) {
    perror ("/dev/evs0");
    exit(10);
  }

  ioctl(evs, EVSIOCADB, &o_dim);
  printf("Current auto-dim brightness: %d, setting it to 0.\n", o_dim);
  n_dim = 0;
  ioctl(evs, EVSIOSADB, &n_dim);
  exit(0);
}
--- cut ---

---
Izumi Ohzawa             [ $@Bg_78^=;(J ]
USMail: University of California, 360 Minor Hall, Berkeley, CA 94720
Telephone: (415) 642-6440     Fax:  (415) 642-3323
Standard mail: izumi@violet.berkeley.edu
NeXTmail:      izumi@pinoko.berkeley.edu